insupportable

from WordNet (r) 3.0 (2006)

insupportable
    adj 1: incapable of being justified or explained [syn:
           {indefensible}, {insupportable}, {unjustifiable},
           {unwarrantable}, {unwarranted}]

from The Collaborative International Dictionary of English v.0.48

Insupportable \In`sup*port"a*ble\, a. [L. insupportabilis: cf.
   F. insupportable. See {In-} not, and {Support}.]
   Incapable of being supported or borne; unendurable;
   insufferable; intolerable; as, insupportable burdens;
   insupportable pain. -- {In`sup*port"a*ble*ness}, n. --
   {In`sup*port"a*bly}, adv.
   [1913 Webster]